3 Answers
3

I conducted some tests using the treasure chest by the waypoint in Cathedral garden. I ran 70 trials. 35 with 31% Gold Find, and 35 with no Gold Find. To sum up the data(which is below), the difference between the gold gotten from the chest with 31% Gold Find and the gold gotten with no Gold Find is 32.99%. So yes, Gold Find does have an effect on the amount of gold from chests, and furthermore, the increase is the same percentage(on average) as the listed Gold Find on your character sheet.

Magic Find and Gold Find seem to work the same way, and since Magic Find affects loot quality in chests, I would assume Gold Find does too

This would probably be easy to test by opening a bunch of treasure chests without gold find, taking note of the average, then realoading the game and opening chests in the same area with gold find. You should see a noticeable increase in gold found.